The present invention relates to a semiconductor transfer and manufacturing apparatus, more particularly, to a semiconductor transfer and manufacturing apparatus equipped with a pressure preserving chamber (load-lock chamber), a vacuum carriage chamber and a carrier robot which transfers wafers between the outside of each apparatus in the atmosphere and a vacuum process chamber.
Recently, faster and smaller semiconductor manufacturing apparatuses are demand. For a semiconductor manufacturing apparatus having a process chamber for processing a wafer in a vacuum, particularly, there is a need for shortening both the time required to transfer wafers within the apparatus and the time required to transfer wafers between the inside and the outside of the apparatus.
FIG. 1 shows a first conventional semiconductor manufacturing apparatus 11. The semiconductor manufacturing apparatus 11 has a process chamber 12, a vacuum transfer chamber 13 and two pre-pressurizing chambers (load-lock chambers which will hereinafter be called xe2x80x9cL/L chambersxe2x80x9d) 14 and 15. Inside the vacuum transfer chamber 13 is a vacuum. A predetermined process is performed on a workpiece or wafer W inside the process chamber 12. The wafer W is transferred to the process chamber 12 via the vacuum transfer chamber 13. The individual chambers 12 to 15 are linked to one another via isolation valves 16.
Carriers 17 and 18 for retaining the wafers W are mounted at predetermined positions in the semiconductor manufacturing apparatus 11. An external transfer robot 19 which transfers wafers W under atmospheric conditions is provided between the L/L chambers 14 and 15 and the carriers 17 and 18. The external transfer robot 19 transfers an unprocessed wafer W or a processed wafer W between the carrier 17 or 18 and the L/L chamber 14 or 15.
An internal transfer robot 20 which transfers wafers within the apparatus 11 (under vacuum) is located in the vacuum transfer chamber 13. The internal transfer robot 20 comprises a base 21, an arm section 22 and a hand section 23. The base 21, which is horizontally rotatable, supports the arm section 22. The arm section 22 has a plurality of joints and is protractable and retractable. The hand section 23 moves horizontally according to the protraction/retraction of the arm section 22. The arm section 22 is also movable up and down. The internal transfer robot 20 has three drive shafts (for vertical movement, turning movement and horizontal movement).
The hand section 23 has a pair of forks 24 on which the wafer W is placed. The internal transfer robot 20 exchanges an unprocessed wafer W placed on one fork 24 with a processed wafer W in the process chamber 12.
FIGS. 2A to 2F illustrate the wafer exchange sequence of the internal transfer robot 20. In this wafer exchange sequence, an unprocessed wafer W1 placed on one fork 24 is exchanged with a processed wafer W2 in the process chamber 12.
The internal transfer robot 20 exchanges wafers W1 and W2 in the following operational sequence.
(1) Extend the arm section 22 until an empty fork 24 reaches a predetermined position in the process chamber 12 (FIGS. 2A and 2B).
(2) Lift the arm section 22 up and place a processed wafer W2 on the fork 24. Then, retract the arm section 22 (FIGS. 2B and 2C).
(3) Turn the arm section 22 180 degrees (FIGS. 2C and 2D).
(4) Extend the arm section 22 until an unprocessed wafer W1 comes to a predetermined position in the process chamber 12 (FIG. 2E).
(5) Lower the arm section 22, place the wafer W1 in the process chamber 12 and then retract the arm section 22 (FIG. 2F).
By executing the steps (1) to (5), the internal transfer robot 20 exchanges the processed wafer W2 placed on the hand section 23, with an unprocessed wafer W1 in the L/L chamber 14 or 15. In this manner, wafers W1 and W2 are exchanged between the L/L chambers 14 and 15 and the vacuum transfer chamber 13 and between the vacuum transfer chamber 13 and the process chamber 12 in the semiconductor manufacturing apparatus 11.
That is, the single hand section 23 serves as a buffer for exchanging wafers W in this semiconductor manufacturing apparatus 11.
FIG. 3 is a schematic plan view of a second conventional semiconductor manufacturing apparatus 31. The same reference numerals are given to those components of the semiconductor manufacturing apparatus 31 which are the same as the corresponding components of the semiconductor manufacturing apparatus 11 in FIG. 1.
An internal transfer robot 32 which transfers wafers within the apparatus 31 under the vacuum condition is located in the vacuum transfer chamber 13. This internal transfer robot 32 has one more set of a drive shaft and an arm than the robot 20 in FIG. 1 in order to decrease the time required for exchanging wafers W.
That is, the internal transfer robot 32 comprises a base 33, two arms 34a and 34b, which respectively support hand sections 35a and 35b. The base 33, which is horizontally rotatable, supports the arms 34a and 34b in a vertically movable manner. The arms 34a and 34b has a plurality of joints. As the arms 34a and 34b protract and retract in accordance with the movement of the joints and the hand sections 35a and 35b each move horizontally. The internal transfer robot 32 has four drive shafts for moving the hand sections 35a and 35b, namely a single drive shaft for vertical movement, a single drive shaft for turning movement and two drive shafts for horizontal movement.
FIGS. 4A to 4D illustrate the wafer exchange sequence of the internal transfer robot 32. In this operational sequence, an unprocessed wafer W1 placed on one hand section 35b is exchanged with a processed wafer W2 in the process chamber 12 in the following steps (1) to (3).
(1) Extend the arm 34a until the empty hand section 35a reaches a predetermined position in the process chamber 12 (FIG. 4B).
(2) Lift the arm 34a up and hold the processed wafer W2. Then, retract the arm 34a. Extend the arm 34b until the unprocessed wafer W1 comes to a predetermined position in the process chamber 12 (FIG. 4C).
(3) Lower the arm 34b, place the wafer W1 in the process chamber 12 and then retract the arm 34b (FIG. 4D).
The internal transfer robot 32 simultaneously performs the operation of transferring the processed wafer W2 to the vacuum transfer chamber 13 from the process chamber 12 and the operation of transferring the unprocessed wafer W1 from the vacuum transfer chamber 13 to the process chamber 12. This makes the transfer sequence of the semiconductor manufacturing apparatus 31 faster than that of the semiconductor manufacturing apparatus 11 in FIG. 1. In addition, unlike the semiconductor manufacturing apparatus 11 in FIG. 1, the semiconductor manufacturing apparatus 31 need not turn the internal transfer robot 32.
As apparent from FIGS. 1 and 3, however, the vacuum transfer chamber 13 accommodates the internal transfer robot 20 or 32, so that the size of the site area for the vacuum transfer chamber 13 with respect to the site area of the whole semiconductor manufacturing apparatus is greater than that of each of the process chamber 12 and the L/L chambers 14 and 15. As wafers become larger, the wafer transfer distance increases. The increased transfer distance requires an increase in the arm length of the internal transfer robot, thus resulting in an increased site area for the vacuum transfer chamber 13. If the vacuum transfer chamber 13 is enlarged to accommodate an increase in the diameter of wafers, therefore, the size of the semiconductor manufacturing apparatus 11 or 31 increases significantly.
Accordingly, it is an object of the present invention to provide a semiconductor manufacturing apparatus which prevents the site area of a transfer robot from increasing to accommodate a larger wafer and improves throughput.
To achieve the above objective, the present invention provides a transfer apparatus for transferring a plurality of workpieces. The transfer apparatus includes a plurality of units and a transfer robot. The units are arranged along a predetermined imaginary circle. The transfer robot has a plurality of arms arranged hierarchically for respectively supporting the plurality of workpieces. The transfer robot transfers the workpieces to the units. The arms are rotatable along the imaginary circle and movable upward and downward.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.